Substrate polishing end point detection methods may use an estimate of the torque required to rotate a polishing pad against a substrate held within a polishing head to determine when sufficient substrate material has been removed. Existing substrate polishing systems typically use electrical signals from the actuator (e.g., motor current) to estimate the amount of torque required to rotate the pad against the substrate. The inventors of the present invention have determined that in some circumstances such methods may not be accurate enough to determine consistently when an end point has been reached. Accordingly, improvements are needed in the field of substrate polishing end point detection.